|A turbot fish is similar to a skyscraper and
2 string kite. The only difference is the shape.
A turbot fish is a single candidate chain (9 in this
example). The blue cells are the ends of the chain.
Each end cell must be strongly linked to a yellow cell.
The two yellow cells must be linked (weak or strong).
This forces one of the blue cells to be a 9 (possibly
both blue cells are 9's). This eliminates the slashed
9 in r6c9.
Skyscrapers, 2 string kites, and turbot fish are all
X chains. They just happen to have just three links
in the chain. They are defined by the orientation of the
strong links as follows:
Skyscrapers - strong links are parallel (both are either rows or columns)
2 string kite - - strong links are perpendicular (one is in a row, one is in a column)
Turbot fish - one of the strong links is in a box, the other is in a row or column